This invention relates to iminodiacetonitrile (IDAN). More specifically this invention is directed to an improved process for preparing IDAN.
Eschweiler described a method (Ann. 1894, 278, 229-239) wherein IDAN is formed by the reaction of hexamethylenetetramine (HMTA) and HCN in an aqueous medium.
Other methods for preparing IDAN are taught by U.S. Pat. No. 3,167,580 (Saunders et al, 260/465.5), U.S. Pat. No. 3,412,137 (Stutts, 260/465.5), U.S. Pat. No. 2,794,044 (Miller, 260/465.5), U.S. Pat. No. 2,511,487 (Thompson, 260/465), and Canadian Pat. No. 684,850 (Koenig).
Saunders et al, and Miller replaced the HMTA of Eschweiler with formaldehyde and ammonia while Stutts used Eschweiler's reactants (HMTA and HCN) in aqueous acetic acid.
Thompson prepares IDAN by reacting aminoacetonitrile (glycinonitrile) with formaldehyde cyanohydrin (glycolonitrile) in the presence of a mineral acid stabilizer.
Koenig prepared IDAN by: (a) reacting HMTA or the amounts of formaldehyde and ammonia required for the formation thereof with HCN in the presence of a solvent (e.g., water); and (b) subsequently acidifying the reaction mixture with a strong mineral acid.